2) A ball is thrown straight up into the air and passes a window 3 seconds after being released. It passes the same window on its way back down 1.5 seconds later. What was the initial velocity of the ball?

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space. b. we'll know it immediately because it will be brighter than the full moon in the sky. c. we won't know about it until 600 years from now. d. none of the above.

A100-watt light bulb illuminates a solar cell. the electricity from the solar cell operates a water pump that delivers 1 watt of power. what is the efficiency of the system?

Which of the following best describes internal energy? a. the difference between the kinetic and potential energies of the particles in a system b. the sum of the kinetic and potential energies of the particles in a system c. the sum of the kinetic and thermal energies of the particles in a system d. the difference between the kinetic and thermal energies of the particles in a system